California utilities are turning to virtual power plants to store renewable energy in batteries during the daytime, and redistribute it later. Companies such as PG&E, SCE and Sempra Energy are testing a grid of solar panels, battery storage, two-way communication devices and software to help correct the supply-demand issue.

During the day, solar and wind energy sources create excess power, often driving wholesale prices to zero. When demand spikes after dark, prices can soar to as much as $1,000 per megawatt-hour.

Communication and control technology is used to create one larger system out of several distributed energy assets. Though currently more expensive than natural gas peaker plants, as technology evolves, the cost of stored battery power is expected to decrease.

Examples include:

Morgan Stanley’s One Maritime Plaza in San Francisco hybrid electric building